Porsche's 918 Spyder has been unveiled at the Frankfurt motor show in its final production form.

Set to go into production soon, the 344kph petrol-electric hybrid two-seater is planned to be built in a run of no more than 918 examples, in left-hand drive only, over the next 18 months.Porsche claims orders for its new performance flagship are ahead of expectations. “We have taken deposits for more than two-thirds of the planned production volume,” officials revealed to Autocar. “Interest is increasing by the day.”

First revealed as a concept car at the 2010 Geneva motor show, the 918 Spyder is based around a carbonfibre monocoque, comes clothed in composite plastic body panels and uses a bespoke chassis fashioned from aluminium, magnesium and titanium.This combination has helped Porsche achieve a kerb weight of 1634kg for the 918 Spyder in its lightest form, despite the inherent complexity and bulk of its petrol-electric hybrid powertrain and battery pack.Removable roof panels that stow away in the nose section allow the new Porsche to be used either as a coupé or a roadster, while an optional Weissach performance package brings a series of aerodynamic tweaks. These include winglets to the bumpers for added downforce, as well as a number of lightweight components, including magnesium wheels, that combined to reduce the kerb weight by 35kg over the standard model.

The 918 Spyder is powered by a plug-in petrol-electric hybrid drivetrain based around a mid-mounted, naturally aspirated 4.6-litre V8 petrol engine that produces 599bhp at 8700rpm. It is supported by two electric motors, one sited up front within the front axle and another at the rear, developing a combined 282bhp at 6500rpm.

All up, the 918 Spyder has a total system output of 875bhp at 8500rpm, which equates to a power-to-weight ratio of 535bhp per tonne and makes the new model the most powerful Porsche road car to date. Maximum revs for the V8 combustion engine, whose aluminium block is based around the unit used in Porsche’s earlier LMP race car, is 9100rpm.The maximum torque of the hybrid system varies between 93.4kgm and 130.3kgm, depending on the gear in use. Drive is channelled through a seven-speed dual-clutch automatic gearbox either to the front wheels under electric propulsion only or all four wheels with a combination of petrol and electric power.

Energy for the electric motors is provided by a 6.8kW/hr lithium ion battery mounted low down at the rear of the monocoque and backed by a four-year guarantee. It is charged both through plug-in means and electrical energy stored under braking.The three power sources are controlled by a Porsche-developed electronic management system offering five different driving modes: E-power, Hybrid, Sport Hybrid, Race Hybrid and Hot Lap.

E-power provides zero-emissions propulsion in front-wheel drive electric mode for distances of up to 32km. So configured, the new Porsche accelerates to 100kph from a standstill in under 7.0sec and reaches a top speed of 150kph.

Porsche says that in Race Hybrid mode, the 918 Spyder will storm from 0-100kph in just 2.8sec — a significant 0.9sec faster than the V10-powered Carrera GT supercar, built from 2004-2007 — with 200kph coming up in 7.7sec and 300kph in 22.0sec. Top speed, aided by active aerodynamics, is put at 344kph — a figure that makes the 918 Spyder the fastest Porsche road car yet.